Audio systems such as consumer electronic portable devices including smart phones and digital media players have a headphone or earphone jack through which the portable device can interface with an accessory device, such as a directly powered headset. An audio integrated circuit referred to as an audio codec is used within the portable device, to convert digital audio files and digital audio streams into analog form, which is then driven by an audio power amplifier whose output is coupled to a speaker signal pin or contact of the headphone jack. In addition, the audio codec also includes the capability of converting an audio signal from analog into digital form, where the input analog signal can be obtained from an integrated microphone within the headset that is plugged into the headphone jack. The audio codec is typically equipped with several such audio channels, allowing digital audio to be played back through either the earpiece receiver in the case of a smart phone, a speakerphone, or through the headphone jack to external earphones. It has also been suggested that the earphone jack be used to attach the audio system to a standalone device such as a self-powered speaker, a television, or a home theater audio amplifier/receiver.